1. Field of the Invention
The present invention relates to a transparent support, an optical film, a polarizing plate and an image display device.
2. Description of the Related Art
With recent progress toward a large-screen liquid crystal display device (LCD), a liquid crystal display device having disposed thereon an optical film such as antireflection film or light-diffusing sheet is increasing. For example, in various image display devices such as liquid crystal display device (LCD), plasma display panel (PDP), electroluminescent display (ELD) and cathode ray tube display device (CRT), the antireflection film is disposed on the display surface so as to prevent the reduction in contrast due to reflection of outside light or disturbing reflection of an image. Also, the light-diffusing sheet is used for a backlight of a liquid crystal display device.
As for the antireflection film, an antiglare film is being widely used in the market at present. The antiglare film is generally produced by a method of adding an inorganic or organic fine particle to an antiglare layer and thereby providing unevenness to the surface. However, the antiglare film produced by this method suffers from a poor jet-black color of the film surface and sometimes impairs the quality when disposed on the display surface.
On the other hand, there is disclosed a method of imparting unevenness to the substrate itself and providing a hardcoat layer or an antireflection layer thereon to obtain an antiglare film having an antiglare effect without providing a special antiglare layer. For example, a technique of incorporating a fine particle into a substrate film to form a surface uneven profile, thereby imparting an antiglare property to an antireflection film, is disclosed (see, JP-A-2005-156801 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)).
The antireflection film using a fine particle disclosed in JP-A-2005-156801 may be imparted with an antiglare property, but when the produced antireflection film is disposed on an image display device, the screen may suffer from reduction in the contrast or occurrence of glare. Therefore, improvements are demanded.
Also, in the case where the antiglare film of JP-A-2005-156801 is used on the surface of a liquid crystal display device (LCD), if a three band fluorescent lamp is reflected on the display surface, rainbow unevenness appears in the periphery of the reflected fluorescent lamp. In this respect, improvements are demanded.
Furthermore, in recent years, saving of the cost involved in a liquid crystal display device is being strongly demanded. In particular, it is demanded to reduce the number of members, for example, in the case of a member participating in the display, to use a member where functions of a plurality of members are integrated or to form polarizing plates in the front and back sides from a common species.